A new Yale University study indicates that cell-to-cell transmission of HIV particles contributes to the development of full-blown AIDS and helps predict which anti-retroviral therapies will be most effective at keeping the disease at bay.

The new research reinforces recent findings that a heavy concentration of the virus at the point of contact between cells is crucial to the development of AIDS. The study also suggests that earlier findings that anti-retroviral therapy fails to suppress HIV at cell junctions might be premature. In their new exhaustive analysis of 16 anti-retroviral drugs researchers showed that 13 are effective. Three drugs were effective chiefly reducing viral levels of free-floating HIV, but they fail to suppress HIV spread from cell to cell. However, researchers found that if two of the three that fail are combined they also suppress the spread of HIV, explaining why existing combination anti-viral therapies are effective.

Senior author Walther Mothes, associate professor of microbial pathogenesis, said the effectiveness against highly concentrated HIV should be tested by companies developing more powerful therapies to combat AIDS. The full study may be read in PLOS Pathogens.